Image acquisition

• Field works
• Terrestrial photography
• Scanning of the photography

Terrestrial photography

• Stereoscopic b/w image sequences were taken from the glacier using a 135-size camera (Nikon FG-20). The length of the stereoscopic base was approximately 25 meters and the distance from the point where the photography was taken to the glacier was most times over 1000 meters.
• The image sequences were taken in a panoramic way using a f = 500 mm tele objective (Tamron 500 SP). This was done in order to record each sequence with both maximum viewing angle and maximum image scale. In order to reinforce the block geometry, the same view was photographed with an objective of  shorter focal length f = 200 mm (Tamron 2).
• The photography was done for the first time in Summer 1994 and then repeated in 1995 and 1998.

Figure 1.  An image sequence taken with a  f = 500 mm tele objective for detailed texture mapping. The image is a mosaick of 13 images.

Figure 2. The same field of view taken with a f = 200 mm lens. This sequence is primarily used for geometric triangulation purposes.

Scanning of the photography

• The images of 1995 and 1996 were first enlarged to paper prints of size 11 x 17 cm and then digitized using a document scanner (UMAX UC 1200S UltraVision). The scanning resolution was 150 ppi which corresponds a pixel size 0,167 mm.
• The images of 1998 have been digitized directly from the negatives and printed to CD's.